You can setup your Book of Shadows on a yearly basis, which would include the entire year’s eight sabbat and moon rituals in one section. Others might be prefer to compile all the sabbat and esbat rituals in their BOS for safekeeping and reference.
What should you include?
The date and time for your ritual. Some pagans will celebrate on the specific day, but it’s a celebration. Therefore, you can celebrate a few days before or after, if you need to. Adding the date/time will allow you to take notes on the weather and reason why you picked the date/time, such as accommodating others to weather problems.
History of the Sabbat. For instance, you’d include for Imbolc, or Imbolg, that’s its also referred to Candlemas, and celebrates the first signs of spring. Look up information on the holiday and add the information that appeals to you.
Plan for crafts, recipes, and ritual supplies. Make sure you keep the list of these items for future reference.
I would also recommend keeping each craft and recipe on its own separate page or put on index cards and stored in envelopes on a page. Some crafts work great on other holidays, and some recipes can be used on off-holiday days as well.
Add moments that moved you, visions you may have, epiphanies, prayers, chants, and invocations you’ve included.
Add spells or other forms of magick worked in ritual. You can add these to an envelope, or you can fold the spell up and seal with sealing wax if you wish to keep it secret. They can be in a separate page or added as a journaling block.
Add graphics and pictures. You can paste these in your BOS with double-sided sticky tape, a gluestick, or use things like stamps to add to your pages.
Here you can also add such elements as quotes, sayings, or just words that have meaning to you. I would add quotes from the funny things some of my friends say during ritual.
And most of all- have fun with it!